From base transitions to expanded editing tools: development and applications of plant base editors.

Plant base editing enables targeted nucleotide substitutions and provides a powerful approach for functional genomics and crop improvement. The toolkit has expanded from canonical cytosine and adenine editors to dual-base, transversion, Cas12-based, and organelle-targeted systems, broadening the range of accessible mutations and genomic targets. These advances create new opportunities for generating useful alleles, modifying gene function, and enabling directed evolution. However, expanded base-editing capabilities do not necessarily ensure predictable outcomes or successful breeding applications. This review summarizes the development of plant base editors, computational tools for target design, and their applications in crop research. We examine editor architectures and compare editing efficiency, product purity, and specificity, with particular attention to transversion editing. We also highlight the intrinsic technical limitations of base editors and the bottlenecks encountered when moving from laboratory research to field applications. By connecting base editor development with practical constraints, this review provides guidance for editor selection and identifies priorities for applying base editing to crop improvement.